optionconverter.h

功能非常强的写日志程序

/*
 * Copyright 2003,2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
#ifndef _LOG4CXX_HELPER_OPTION_CONVERTER_H
#define _LOG4CXX_HELPER_OPTION_CONVERTER_H

#include <log4cxx/helpers/tchar.h>
#include <log4cxx/helpers/objectptr.h>

namespace log4cxx
{
	class Level;
    typedef helpers::ObjectPtrT<Level> LevelPtr;

	namespace spi
	{
		class LoggerRepository;
		typedef helpers::ObjectPtrT<LoggerRepository> LoggerRepositoryPtr;
	} 

	namespace helpers
	{
		class Properties;

		class Object;
		typedef ObjectPtrT<Object> ObjectPtr;

		class Class;

		/** A convenience class to convert property values to specific types.*/
		class LOG4CXX_EXPORT OptionConverter
		{
			static String DELIM_START;
			static TCHAR DELIM_STOP;
			static int DELIM_START_LEN;
			static int DELIM_STOP_LEN;

		/** OptionConverter is a static class. */
		private:
			OptionConverter() {}

		public:
			static String convertSpecialChars(const String& s);

			/**
			If <code>value</code> is "true", then <code>true</code> is
			returned. If <code>value</code> is "false", then
			<code>true</code> is returned. Otherwise, <code>default</code> is
			returned.

			<p>Case of value is unimportant.
			*/
			static bool toBoolean(const String& value, bool dEfault);
			static int toInt(const String& value, int dEfault);
			static long toFileSize(const String& value, long dEfault);
			static const LevelPtr& toLevel(const String& value,
				const LevelPtr& defaultValue);

			/**
     		Find the value corresponding to <code>key</code> in
     		<code>props</code>. Then perform variable substitution on the
     		found value.
			*/
			static String findAndSubst(const String& key, Properties& props);

/**
Perform variable substitution in string <code>val</code> from the
values of keys found in the system propeties.

<p>The variable substitution delimeters are <b>${</b> and <b>}</b>.

<p>For example, if the System properties contains "key=value", then
the call
<pre>
String s = OptionConverter.substituteVars("Value of key is ${key}.");
</pre>

will set the variable <code>s</code> to "Value of key is value.".

<p>If no value could be found for the specified key, then the
<code>props</code> parameter is searched, if the value could not
be found there, then substitution defaults to the empty string.

<p>For example, if system propeties contains no value for the key
"inexistentKey", then the call

<pre>
String s = OptionConverter.subsVars("Value of inexistentKey is [${inexistentKey}]");
</pre>
will set <code>s</code> to "Value of inexistentKey is []"

<p>An IllegalArgumentException is thrown if
<code>val</code> contains a start delimeter "${" which is not
balanced by a stop delimeter "}". </p>

@param val The string on which variable substitution is performed.
@param props The properties from which variable substitution is performed.
@throws IllegalArgumentException if <code>val</code> is malformed.
*/
			static String substVars(const String& val, Properties& props);

			/**
			@param key The key to search for.
			@param def The default value to return.
			@return the string value of the system property, or the default
			value if there is no property with that key.
			*/
			static String getSystemProperty(const String& key, const String& def);

			/**
			Instantiate an object given a class name. Check that the
			<code>className</code> is a subclass of
			<code>superClass</code>. If that test fails or the object could
			not be instantiated, then <code>defaultValue</code> is returned.

			@param className The fully qualified class name of the object to instantiate.
			@param superClass The class to which the new object should belong.
			@param defaultValue The object to return in case of non-fulfillment
			*/
			static ObjectPtr instantiateByClassName(const String& className,
				const Class& superClass, const ObjectPtr& defaultValue);

			static ObjectPtr instantiateByKey(Properties& props,
				const String& key, const Class& superClass,
				const ObjectPtr& defaultValue);

			/**
			Configure log4cxx given a configFileName.

			<p>The configFileName must point to a file which will be 
			interpreted by a new instance of a log4cxx configurator.

			<p>All configurations steps are taken on the
			<code>hierarchy</code> passed as a parameter.

			<p>
			@param configFileName The location of the configuration file.
			@param clazz The classname, of the log4cxx configurator which
			will parse the file <code>configFileName</code>. This must be
			a subclass of Configurator, or null. If this value is null then
			a default configurator of PropertyConfigurator is used, unless the
			filename pointed to by <code>configFileName</code> ends in '.xml',
			in which case DOMConfigurator is used.
			@param hierarchy The Hierarchy to act on.
			*/
			static void selectAndConfigure(const String& configFileName,
				const String& clazz, spi::LoggerRepositoryPtr& hierarchy);
		};
	}  // namespace helpers
}; // namespace log4cxx

#endif //_LOG4CXX_HELPER_OPTION_CONVERTER_H